Control Limits for Individual Measurement and Moving Range Charts
Control limits for Individual Measurement charts are computed as follows:
LCL for Individual Measurement Chart = 
UCL for Individual Measurement Chart = 
Control limits for Individual Measurement charts with sigma estimated by the median moving range are computed as follows:
LCL for Individual Measurement Chart = 
UCL for Individual Measurement Chart = 
Control limits for Moving Range charts are computed as follows:
LCL for Moving Range Chart = 
UCL for Moving Range Chart = 
Control limits for Median Moving Range charts are computed as follows:
LCLMMR = max(0, MMR - Kd3(n)
)
UCLMMR = MMR + Kd3(n)
The standard deviation for Individual Measurement and Moving Range charts is estimated as follows:
The standard deviation for Individual Measurement and Moving Range charts when using the median is estimated as follows:
= MMR/0.954
where:
= the mean of the individual measurements
K = the sigma multiplier and is set to 3 by default
= the mean of the nonmissing moving ranges computed as (MR2+MR3+...+MRN)/(N-1) where MRi = |xi - xi-1|.
MMR = the median of the nonmissing moving ranges
σ = the process standard deviation
d2(n) = expected value of the range of n independent normally distributed variables with unit standard deviation.
d3(n) = standard deviation of the range of n independent normally distributed variables with unit standard deviation
Note: Moving Range charts in Control Chart Builder use a range span of n = 2.